Process optimization and techno‐economic evaluation of a nanomembrane– AOP hybrid semi‐pilot system for antibiotic abatement

Abstract A continuous hybrid treatment system on integration of cross‐flow flat‐sheet nanofiltration (NF) membrane system with persulphate‐based oxidation was developed for efficient removal and degradation of antibiotic residues from water. The cross‐flow configuration significantly reduced fouling through enhanced surface sweeping, enabling stable operation. Antibiotic rejection increased with transmembrane pressure and cross‐flow rate, confirming uncoupled solute–solvent transport in NF. Maximum permeate fluxes of 352, 188, and 136 L m −2 h −1 were obtained for NF‐2, NF‐20, and NF‐1 membranes, respectively, at 14 bar and 800 LPH. Overall rejection exceeded 96%–98%, following the order azithromycin > ofloxacin > ciprofloxacin. Azithromycin rejection was dominated by steric hindrance, while ciprofloxacin and ofloxacin were mainly rejected through Donnan and electrostatic exclusion mechanisms. Optimal performance was achieved at pH 9, where all antibiotics existed in anionic form and strong charge repulsion dominated separation. The NF concentrate was subsequently treated using persulphate oxidation, and process parameters were optimized via response surface methodology. Under optimized conditions (persulphate 6.1 mg L −1 , flow rate 36 mL min −1 , residence time 40 min), degradation efficiencies of 98.88% for azithromycin, 97.96% for ofloxacin, and 97.65% for ciprofloxacin were achieved. The results demonstrate a robust, low‐fouling, and scalable tertiary treatment strategy for antibiotic‐contaminated water.